Adult Acute Lymphoblastic Leukemia: 2025 Update on Diagnosis, Therapy, and Monitoring

Acute lymphoblastic leukemia (ALL) is a disease of lymphoid progenitor cells arising in the bone marrow and extramedullary sites. While it is the most common pediatric cancer, ALL is a rare disease overall, with approximately 6500 new cases diagnosed in the United States, in 2024. Current treatment relies on multiagent chemotherapy administered over 2-3 years, resulting in long-term survival in 80%-90% in pediatric patients compared to 40%-50% in adult patients, depending upon patient- and disease-specific characteristics.

Historically considered a poor risk ALL subtype, the treatment and outcome of Philadelphia chromosome (Ph)-positive B-cell ALL were drastically changed with the advent of the BCR::ABL1 tyrosine kinase inhibitors (TKIs). The combination of a TKI with a backbone of multiagent chemotherapy, or more recently blinatumomab, is the mainstay of therapy, resulting in 5-year survival rates of 80+%. Achieving a complete molecular remission, particularly by next generation sequencing, is an important prognostic indicator, which may identify patients who may avoid allogeneic stem cell transplantation (SCT).

The treatment approach for patients with Ph-negative B-cell ALL was historically composed of a chemotherapy backbone (either pediatric-inspired, or Hyper-CVAD based). Novel agents including inotuzumab ozogamicin and blinatumomab are being incorporated into these regimens to improve the rates of measurable residual disease negativity and long-term outcomes. While differences in long-term survival rates differ between age groups, such as adolescents and young adults compared to older adults (≥ 60 years), with these immunotherapy-chemotherapy regimens, the 4-year survival rates have improved to 80%-85% among patients who are able to receive these treatments. Elderly patients represent a difficult population to treat due to poor chemotherapy tolerance, high-risk disease features, and increased risk of developing therapy-related myeloid neoplasms. The use of inotuzumab ozogamicin and blinatumomab in lieu of intensive chemotherapy in this population has improved safety and efficacy in patients ≥ 60 years old. Clinical trials incorporating chimeric antigen receptor (CAR) T-cell therapy into treatment for older patients are in progress.

Combination chemotherapy regimens incorporating pegylated asparaginase and nelarabine are the standard for patients with T-cell ALL. Early T-cell precursor (ETP) ALL is a high-risk subgroup for which allogeneic SCT should be considered. Inclusion of the BCL-2 inhibitor venetoclax into treatment for patients with ETP-ALL may be beneficial and is currently being investigated.

Several therapies are approved as single agents in the salvage setting. However, the best outcomes are obtained with combination therapy including chemo- and immuno- therapies followed by CAR T-cell consolidation and allogeneic SCT. Clinical trials optimizing this approach are ongoing.